There is a great need for catalyst compounds that are suitable for polymerization of olefins in the presence of polar additives.
The polyolefin industry works with processes that polymerize ethylene as well as other non-polar 1-olefins with the aid of various catalysts and radical initiator systems. These polymerizations can be carried out using organometallic Ziegler-Natta coordination catalysts, chromium catalysts and most recently metallocene-type compounds of early transition metals, as well as radical initiators. Furthermore, it has been found that these catalysts react very sensitively to a number of substances that impair or entirely prevent catalytic activity. For example, it is known that traces of oxygen, carbon monoxide, water or oxygen-containing organic compounds, which act as donors, can deactivate these catalysts. If these substances are present, the use of catalysts is normally limited to radical initiator systems.
To improve these circumstances and also to copolymerize polar monomers, catalysts based on late transition metals were developed. Summary articles can be found in Mecking, S. Angew. Chem. 2001, 113, 550; Ittel, S.: Johnson, L. K. and Brookhart M. Chem. Rev. 2000, 100, 1169 and Boffa, L. S.; Novak, B. M in Chem. Rev. 2000, 100, 1479.
Typically, the complex types used are divided into those with anionic ligand structures or those with neutral ligand structures. The group of complexes with an anionic ligand structure shows particularly robust properties with regard to the above-mentioned catalyst, as a result of the uncharged (neutral) active polymerization species. This is a result of the low Lewis acidity of the catalytic species. Current research interest is therefore focused precisely on these catalyst types. Thus in J. Angew. Chem. 1987, 99, 76, Ostoja Starzewski and K. A. Witte disclosed such catalysts with a [P,O]-ligand type. Klabunde, U.; Ittel, S. D. report of similar catalysts in J. Mol. Catal. 1987, 41, 123. Comparable catalysts [P,O] complexes are disclosed also in U.S. Pat. No. 5,175,326.
A new catalyst class A, similar in conception to [P,O]-complexes, was developed which, instead of the phosphorus donor, has an iminic nitrogen donor.

Large steric groups R and R″″, which screen off the apical positions around the metal centre as far as possible are a common feature.
The corresponding processes for the production of such catalysts are disclosed in more detail in WO 98/30609, WO 98/42664, WO/98/42665, DE-A 199 61 340, WO 00/56785, WO 01/92347 and WO 02/08236.
Surprisingly, it was found that special azo dyes can also be inserted into the series of anionic ligand systems for complexing. Azo dyes represent a class of compounds that have already been thoroughly investigated, and that can also be synthesized on an industrial scale.
In Macromolecules, 2002, 35, 6071, von Schröder, D. L.; Keim, W.; Zuideveld, M. A.; Mecking, S. disclose this kind of ligand for the production of single-site catalysts for the polymerization of olefins. However, activation with the widest variety of Lewis acids in the presence of polar additives and sterically demanding ortho-substituted compounds, which have an influence on activity and molar mass, are not disclosed.
EP-A 1 170 308 discloses ligands that also have an azo-function but, in contrast to the present invention, have no oxygen-metal bond, but an amide-like nitrogen-metal bond. Nor are transition metal compounds with late transition elements disclosed. No sterically demanding substituents in ortho positions to amide-like nitrogen in such complexes are disclosed.
DE 1 232 747 B2 discloses a monometallic, chelating azo ligand, which in addition to the azo donor function, has a metal-carbon (phenyl) bond, in other words a carbanionic phenyl-metal bond rather than an oxygen-metal bond. As metal-phenyl bonds of nickel are demonstrably polymerization-active, the complex postulated in DE 1 232 747 B2 would not effect a chelate-like coordination of the metal centre during polymerization. A disadvantage of this process is therefore the change in the geometry of the metal complex during polymerization. Thus good results cannot be expected with regard to polymer uniformity.
The present invention provides catalysts that allow olefin (co)polymerization in the presence of polar additives.